initrd with rootfs autodetect

[Francois-Rene Rideau]

OK, so I modified the bootdisk so as to autodetect a possible rootfs,
and if found, to chain into it, freeing the ramdisk.

Features:
* it initializes the console correctly :-)
* it will use fdisk partition tags to detect which partition
 is linux or DOS.
* it will auto-install all required files to make the partition bootable
 if the partition exists and is formatted but otherwise empty.
* you can disable autodetection by creating a file or directory
 "noautomount" in your DOS partition.
* it makes attempts to detect abnormal situations and provide safe fallbacks

Issues:
* it will try to use blockdev to free the ramdisk memory,
 but the required utility blockdev isn't part of busybox :(
* somehow, my linuxrc script is executed as PID=9, so I can't use pivot_root
 and link into a debian's sysvinit, or it will be confused.
 Hence, we must use change_root. Darn!
* Oleg: how do you do, here? Do you use pivot_root with busybox's init?
* Oleg: somehow, I can't login on your TAR.bz2 image. pam rejects me.
 Yet, somehow, the passwd field seems to be empty (!)
 Until I understand this issue, I have rcS openvt -c 11 /bin/bash
* tested by me only -- tell me what doesn't work!

[ François-René ÐVB Rideau | Reflection&Cybernethics | http://fare.tunes.org ]
[  TUNES project for a Free Reflective Computing System  | http://tunes.org  ]
A computer is like an Old Testament god, with a lot of rules and no mercy.
	-- Joseph Campbell